Filtrete 12x24x1 MPR 300 Air Filter, made by 3M, helps capture unwanted particles from your household air to contribute to a cleaner, fresher home environment. Made with exclusive Filtrete 3-in-1 technology, including an MPR 300 and MERV 5 rating, your AC filter will help pull and capture lint, household dust and dust mite debris, while letting cleaner air flow through. Use a 3-month pleated 1-inch home HVAC filter in your furnace, air conditioner or HVAC system. For optimal performance, change your furnace filter at least every 90 days.